Method and apparatus for electrolytic shaping



.1.A J. FALLS July 26, 1960 METHOD AND APPARATUS FOR ELECTROLYTICSHAPING Filed NOV. 13. 1956 3 Sheets-Sheet 1'IHIIUIIHU.UllhunhHHHNHHHHHHHHHMHHHHFII INVENToR. @/amv d. 7245 July 26,1960 J. J. FALLS 2,946,731

METHOD AND APPARATUS FOR ELECTROLYTIC SHAPING Filed No`v. 13, 1956 5Sheets-Sheet 2 45 7 s: I 4f H5' i 46 i: i 6 55 I I l 5? 44 i l l s l l'g 9 i I E 43 l IT 4Z l A I l l i l f Il l z I 7 IN V EN TOR.

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July 26, 1960 J. J. FALLS METHOD AND APPARATUS FOR ELECTROLYTIC sHAPINGFiled Nov. 13. 1956 ,/62 Z9 5 fr Jl dof/N d Hubs W/ MN/m J 6 A 2 f 6 w-w/z HHH@NNW 27u ll H M f5 @a United States Patent O METHOD ANDAPPARATUS FOR ELECTROLYTIC SHAPING John J. Falls, Cincinnati, Ohio,assigner to The Standard Electrical Tool Company, Cincinnati, Ohio, acorporation of Ohio Filed Nov. 13, 1956, Ser. No. 621,918

17 Claims. (Cl. 204-143) r[his invention relates to a method andapparatus for shaping metallic objects by the electrolytic process.Elec- .trolytic shaping involves the removal of material from a metallicobject by passing high amperage direct current between a metallicobject, or workpiece, and a rapidly rotating conductive wheel or discmoving in close proximity to the workpiece in the presence of a watersolution of electrolytic salts. With the wheel or disc rotating in verylight contact against the workpiece, material is removed from theworkpiece principally by electro-chemical action rather than by thesnagging action common to the ordinary abrasive wheelmethod. It may besaid material is removed from the workpiece by a deplating or dissolvingprocess which is performed as a direct reversal or opposite, of anyelectroplating process. Thus, in the practice of electrolytic shaping,the rapidly rotating wheel is not pressed into firm contact with theworkpiece, and as a consequence, wearing of the wheel is greatlyminimized. Notwithstanding the reduced pressure of the lwheel or discupon the workpiece, material is removed from the latter at a rapid rate.l

Electrolytic shaping, commonly referred .to as electrolytic grinding,may be performed on a machine simulating the well-known snagginggrinder, which includes a worksupport and -a rapidly rotating grindingwheel or disc, with certain modifications. In the practice ofelectrolytic shaping or grinding, the metallic workpiece isl keptcharged with a lowvoltage high-amperage direct current of positive orplus polarity, while at the same time the electricity-conductivegrinding wheel or disc is kept negatively charged. The workpiece and thegrinding wheel or disc are electrically insulated from one another,except yfor the fact .that the current may passV from one to the otherthrough a bath of liquid electrolyte applied at the area of contactbetween the workpiece and the wheel.

The wheel or disc may be fabricated principally of metal or othercurrent-conductive material, with the working or grinding face thereofprovided with an armor of minutely spaced abrasive particles ofnonconductive material, an example of which is diamond powder or chips,

v which serves to slightly space the conductive material of the wheelfrom.- the workpiece as the wheel rotates lightly against theworkpiece.Y The non-conductive varmor maten'al on the wheelfaceprecludes metal to metal contact between the wheel and the workpiece,thereby maintaining a gap at the workpiece through which the low-voltagecurrent will not -be short-circuited. This gap, however, can be bridgedby. electrolytic fluid fed thereto, to pass current from the workpieceto the rotating wheel in performance of the electrolytic removal ofmaterial from the workpiece. In the process las outlined above, theworkpiece ybecomes the anode in the electrolytic system, and theconductive Wheel becomes the cathode. K

The present invention is concerned with an improved method and means`for keeping Ithe workpiece and the rotating wheel properly chargedcontinuously with op- 0r grinding of the workpiece.

j A 2,946,731 Patented July 26, 196g ice One object of the invention isto impose an electrical charge upon the rotating Wheel in such a manneras to avoid injury to the wheel driving spindle, its bearings, thehousing supporting the bearings, and any other parts or mechanismslassociated with .the spindle.

Another object of the invention is to so impose an electrical chargeupon the rotating wheel, as Vto avoid injurious heating of the wheelspindle and deterioration of its bearings, as well as undesirableinterference with proper operation of any spindle-driving motor whichmay have direct application or connection to the spindle.

A Ifurther object is to provide means for maintaining an electricalcharge upon the rotating wheel without interruption, and with due regardto safe and trouble-free operation of the apparatus.

A still further object of the invention is to achieve the foregoingobjectives and advantages with the use of simple, inexpensive, andhighly elective means requiring a of servicing and shut-down expense,vital parts of the apparatus being so arranged and located that possibledeterioration and damage thereto in service are practically eliminated.i

The foregoing and other objects are attained by the means describedherein and illustrated upon the accompanying drawings, in which:

Pig. l is a side elevational view, partly in cross-section, illustratingan apparatus embodying the present inven tion, and adapted for shapingmetallic objects by the electrolytc process.

Fig. 2 is a fragmentary cross-sectional view on an enlarged scale,showing va portion of an electricity conductive wheel ortdisc utilizedin the grinding apparatus and process of the invention.

Fig. 3 is an enlarged fragmentary cross-sectional View showing detailsof construction at the upper or tail end of the machine spindle.

Fig. 4 is an enlarged fragmentary cross-sectional view showing agrinding wheel mount, this being a modification of the mount shown incross-section at the foot of Fig. 1.

Fig. 5 is a view similar to Fig. 4, showing a. second modification ofthe wheel mount.

Fig. 6 is an elevational view, partly in cross-section, showing theinvention applied to a twin-'wheel spindle.

With reference to the accompanying drawings, Fig. 1 illustrates at 8 amotor housing having opposed end bells 9 and 10 which enclose the fieldwindings and the armature 12 of the motor. To the bell 10 is secured anextending spindle housing 13 containing suitable bearings such as 14 and15, to rotatably support a rotary spindle 16 which extends through thebells and housing 8. Additional tbearing means 17 associated with bell 9may be provided, contributing to .proper support of the spindle, asindicated upon Fig. 3. In the preferred form of the apparatus, the rotoror armature 12 is xedly mounted directly upon the spindle to drive samewhenever the motor is energized.

The tool end, or the workingend 18 of the spindle, is

fashioned and equipped to detachably Ysupport the disc or grinding wheel19, which rotates in a plane transverse to the spindle axis. The disc orwheel is rendered detachable in order to facilitate replacements orsubstituftions as may be required, due to wearing of the wheels, or tovarying characteristics of different Workpieces to be operated upon.Workpieces formed of different types or grades of Various metals may beelectrolytically shaped to advantage, with the use of dilering types orgrades of grinding wheels. Any suitable or elective means may beemployed for detachably mounting the wheel or disc 19 upon the tool endof the spindle, as for example, the socket-head screw 20 whose threadsengage the internally threaded bore 21 in the end of the spindle. Thehead of the spindle end and a marginal portion of the counterbore 23formed centrally of the wheel. A suitable key 24 may be provided, ifdesired, to lock the wheel against rotation relative to-the spindle. f

previously mentioned herein, the grinding wheel or dis .c. is `to carryan .electrical charge, and .will .therefore constructed wholly lorpartly of metal or othercurrent conductive material. ln the form ofwheel or .disc illustrated by Fig. l, the .entire body portion 25 is .ofmetal, and carries aiixed .facing 26 also of metal from which famultitude of nonconductive particles 27 extend (Fig. 2.), The.nonconductive particles may be s tones, such .asdiamond chips or thelike, minutely spaced apart and extended equal distances from the facing.material 26 as indicated upon Fig. 2, so that .the particles 27 .maycontact.aworkpiece without placing the conductive `facing Z6 inactualelectrical 4contact with the workpiece. A typical workpiece is indicatedat W in Fig. l.

From the.foregoing, .it .Will readily b e understood that .the particles27 of nnonconductive vrmaterial electrically insulatethe metallic wheelfrom the workpiece W, so that a Vlow-.voltage high-amperage electriccurrent may Vnot ordinarily ,pass between .the workpiece and thegrinding tvheelfre's-ti'ng thereon. Howeven'currcnt maybe caused to passbetween the charged wheel .and the Voppositely 1charged workpiece,byintroducing between these elements a water .solution of electrolyticsalts, commonly referred to as electrolyte. The electrolyte may bedirected to the space between-the .wheel and the workpiece in anysuitablemannenasby means of a nozzle 28 in Fig. l, or otherwise aswillbe explained.

Referring to Fig. l, it may be noted that the workpiece Whats electricalvconnection at 29 with the positive pole of ,direct current source ofelectric energy, indicated as a igenerator@ whereas the grinding 4wheelor disc 19, as will be explained, is connected tothe negative pole ofthe 1ge,neratoror.,ou rce of .electric energy. The connection 29,ifgeird, may be applied 'l0 :the @titanic bed 0I' frame 30 of themachine, rather than to the workpiece directly, .provided that theworkpiece is in current conductive cont Vith the .bed or frame duringthe shaping or grinding ope non.

lt highlydesirableito yso impose an electrical charge upon the grindingwheel or disc, vas to avoid various gliiculties Laffecting operation ofthe machine, -and the f. anoperator or attendant. For example, if thetrical @Qlllltctiqtt is miadsfat Vtht grinding l .may be exposed toVchemical or corrosive .estrolrts solution, .the @motion will S0051 il.@il et@ .and ret-lult@ revetement, with @essentiel n i C @liutslgwas 0ftheme'Chlne @ad less '0f produ@- .Onthe other hand, if Vthe electricalconnection be de ata location Vremote from .the electrolyte bath, for e,at the tail .end of the .spindle or upon the casing ,tlie apparatus,.the continuous passage of current th ugh the bearings and ,other vitalparts of the machine v,cause,destructive electrolysis and corrosion ofthe due to electromagnetic interference occurring as the heavy directcurrent Vpasses the field and armature windings of the motor, producingeddy currents and magnetic iields incompatible with those of thealternating-current driving rnptor. At the very high amperages withwhich the electrolytic grinding process is commonly practiced, thedrivmotor subjected. to Ainternal magnetic and electrical interferenceas mentioned above, may be irreparably damaged Withiny a brief period ofusage.

"The present invention has as a primary objective, the lete eliminationof destructive forces such as are I 'oned in the preceding paragraph. Toaccomplish Mm, V thecspindle is provided throughout its length with aboregor passageway 31, in which is supported, in spaced 4substarttial,conccntricity with the wall of the bore, an sloeg??? .rod O r glement32 of ,Copper 0r Qther highly .slgllltlvs @letal 0r matenal- .TheCQnduQtQr wd .32 iS 5, overheating, vandra serious loss of motoreiciency l electrically insulated from the spindle at all points aboveor remote from the region of the grinding wheel or disc 19. In theregion of the Wheel or disc 19, electrical contact may be establishedwith rod 32 in any suitable manner, as by means of a metalliccylindrical bushing 33 which snugly embraces the lower end of the rodand has a close fit within the counterbore 34 of the spindle end. Thebushing may be, steered within the .Spindle @lutterbore, a set screw 3Sbeing suitable for the purpose.

From the ,foregoing explanation, it will be understood that an electriccharge vapplied attheextreme upper ,end idiot-conductor rod 32, will bedelivered directly to the grinding wheel through bushing 33 and theworking end portion 18 of the spindle, without shunting or distributingany portion of the charge to the motor Vp12, the bearings l, 1S, 17, orto'other vital parts of the apparatus. The complete circuit, therefore,would comprise the generator, conductor 37, the workpiece W, theelectrolyte upon the workpiece, thegrinding wheel 19, spindle end 18,bushing 33, *conductor odV 32,/ a drumor ring 38 atop the conductor rod,va brush 39 contacting the drum 38, and a return conductor wire 40leading to the negative terminal of the generator. The drum 38; is ofcourse va conductor Vofcurrent, and has electrical connection with thetai-l end 36' of conductor'rod' 32,2but not with the tail Vend 41 of thespindle.

Fora detailed disclosure of the construction at the tail end ofthe'spindle,vreference may be had to Fig. 3 wherein is `shown the spindlereduced in diameter to accommodate the ,bearing 17,-the inner race .42of which maybe securedto the spindle by means of a nut 43. An end cap d4on the motor casing enclosesrthe bearing, while permitting a portion ofthe spindle end 41 to extend therebcyond for accommodating an adapter 45of 'insulating material, which supports the drum 138 and insulates itfrom the spindle and the motor casing. yThe central bore 46 of theadapter snugly receives the ltail end of -the spindle, and to ensurerotation of the adapter with the spindle,`a set screw 47 or othersecuring device may be furnished. Drum 38 rests atop the insulatingYadapter 45 and may be secured thereto in any suit-able manner, as bymeans of screws 43. A set screw 49 or equivalent means may tix themetallic drum 38 to the tail end l36 of conductor rod 32 as shown. Boththe rum and the adapter are preferably concentric with the conductorrod, the latter extending into an axial bore Sil of the drum whereelectrical Contact is established between Vthe drum and the rod.

From Ythe foregoing, it will readily be evident that an electricalcharge from brush V39 imposed upon the Ydrum 38 will pass to theconductor rod `32, the latter carryingV the charge directly to the toolend of the spindle for transmission to the grinding wheel or disc 19. Aswas previously pointed out, the conductor rod 32. is insulated from thespindle by reason of the air space between the rod and the spindle boreat all locations between the bushing 33 and the tail end of the spindle.ln- -sulation in addition to the air space may be furnished lbyrneans ofone or more insulating sleeves 51, 52, surrounding the conductor rod 32and fitting nicely within 'the axial bore of the spindle. The insulatingsleeve means Sil, 52 may be Vof one continuouslength, if desiredQand thepreferred construction such sleeve means will ex- Itend' continuouslyalong the conductor rod throughout "the length of the motor and itsarmature 12, to bar radiation of` magneticnflux and eddyV currents `fromthe rod to themotor windings and'poles. The insulating sleeve '5.1attttlinglyris Shawn extending from the' lower bell lllll .0f the niet@.Casing t0 the insulating .adapter 4S at Vthe remaining jbell 9. Thetailend ofsleeve 51 may abut from the spindle bearing 17, the adapter 45 maybe provided with a depending annular lip 55 which moves in closeproximity to a cooperative upstanding annular shoulder 56on cap 44 asshown in Fig. 3, .while a depending cylindrical extension 57 of theadapter rides closely within the bore 58 of cap 44.

With reference to Fig. 1, it may be noted that the electrical contactbrush 39, whichbears constantly upon the metallic drum as the drum andspindle rotate in unison, is carried in a brush holder 59 that isinsulated from the motor casing. The brush holder may be stationarilysupported in any suitable manner, as by-means of an insulating bracket60 carried by the motor bell, or cap 44.

With the apparatus constructed as set forth in Figs. 1, 2 and 3, Vthemotor casing 8 should be electrically insulated from the bed or frame30, if the bed or frame is electrically charged through the workpiece W,as shown. This will avoid short-circuiting of the generator currentthrough the motor casing. As an alternative, the workpiece W might beelectrically insulated from the bed or frame, so as to carry thepositive charge without transmitting any portion thereof to4 ythevbed orframe 30, in which event grounding of the motor casing upon the bed orframe would be inconsequential.

The possibility of short-circuiting the generator current may be reducedto a practical minimum by eliminating entirely all metallic contactbetween the grindingwheel and its drive spindle. vTwo methods `ofaccomplishing this are disclosed in the structures exemplified by Figs.

4 and V5. In Fig. 4, the grinding wheel comprises a metallic body 61whichvis electrically insulated completely from the spindle 16, by meansof the dielectric elements 62 and 63. Element 62 is an insulating sleeveitted in the central bore 64 of the body or Wheel 61, the sleeve beingadapted to snugly receive 'the `tool end 18 of the spindle. An'annularflange 65 integral with the sleeve 62 may overlie the wheel body andthereby provide an insulating barrier against the spindle housing 13.'For Asecuring the wheel to` the spindle, a lnut 66 may be applied tothe spindle threads 67, to bearagainst Vtheinsulating washer 63 which inturn abuts the base 68 of a bore 69 inthe wheel. By this means or asuitable equivalent connection, thevgrinding Wheel may be fixed to thespindle for rotation therewith.

As in the previous disclosure, the electricity conductor rod 32 extendsthrough the axial bore or passageway 31 of the spindle, from the workingend or tool end, to the tail 'end where the brush connection from thegenerator is established, as in Fig. 3. A suitable insulating sleeve 70,or a series of such sleeves, may serve, to space and insulate the.conductor rod from the inner wall of the spindle bore. Electric currentapplied at the tail end of ythe conductor rod 32 is transmitted to thegrinding Wheel 61 through a metallic terminal plate 71 which is bored at72 to accommodate the rod, and the connectionmay be rendered secure, inany suitable manner, as by means of a set screw or fastener '73, Itshould be noted that the metallic terminal plate is free of any contactwith the spindle, so that no current may pass to the spindlefrom thecharged plate 71. v

'Ihe terminal plate 71 has electrical connection with the grinding wheel61 at the screw or screws 74, which hold the plate iirmly `against ashoulder 75 ofthe wheel surrounding the bore 69. Electric current sobrought to wheel 61 may readily electrify the ,grinding Wheel facingY76, which `is similar to the facing illustrated by Figs.. 1

and 2. By reason bf the means described, .the grinding wheel and its`facing may be supplied with a negative electrical charge without inanyway charging the spindle, its bearings, .orthe casing elements 13, 10, 8and 9. It will therefore be understood that the motorcasing may be xedto the frame or bed 30 of lthe apparatus without thev use of electricalinsulation, and should an operator or `attendant inadvertently drop awire, chain, or other Imetallic: object onto lthe motor casing andinContact with 'theA machine frame, no dangerous shont-circuitiug of thehigh amperage current could result. The apparatus thereby is renderedsafe to operate, and at the same time the motor, the bearings, and allother vital parts of the apparatus are protected against damage due toelectrolysis and corrosion. The motor in any modiiication of theapparatus, Vis to be protected against damage due to eddyv currents andstray electromagnetic ux emanating from the conductor rod 3-2, bysurrounding the rod with a Ysuitable insulator. This may take the formof a dielectric sleeve such as 51 of Fig. l.

Reverting momentarily to Fig. 4, it may be noted that the hub 77 ofwheel 61 may be encircled -by an opentopped trough 78 into which astream of electrolyte may 'be ted during rotation of the wheel, saidtroughhaving one or more downwardly directed jets or passages 79 to feedelectrolyte continuously to the tacing 76 and any workpiece being groundor scrubbed thereby. The facing element 76 may be secured to .the wheelbody 61 in any suitable manner, as by means of screws 80 passingYthrough holes in the facing and anchoring into .the wheel body. Bypreference, the jets or` passages 79 diverge outwardly from the outerwall ot .trough 78, so that elecvtrolytejfrom, the trough will feed tothe wheel I'facing lautomatically with the aid of gravity andcentrifugal force.

In the inodilied structureV of Fig. 5, the entire body of the .grindingwheel or disc 81 is formed of hard insulation or dielectric material, anexample of which is Micarta,r this wheel comprising Ia hub 82 axiallybored at 83 to snuglyreceive the spindle end 18. A nut 84 appliedtoscrewthreads 85 on the spindle, bears against a suitable washer, 86 toiixedly mount the Vgrinding Wheel upon the spindle for rotationtherewith.

As in thev previous disclosures, an electrical charge carried tothe tailend of conductor rod 32 by the brush 39, is transmitted by said roddirectly to a terminal plate 87 of metal, Ahoused within a'bore 88 ofthe wheel body. By means `of screws 89 .and 90, or other appropriateexpedient, the terminal plate 87 may be held in electrical contact Withthe wheel facing 91 and the tool end of the rod, as shown. N either therod 32 nor the terminal plate 97 is to be in electrical contact lwith4the spindleend or its nut 84.' Screws or other fasteners 92 inadddition to those indica-ted' at 89, may be employed for holding thefacingelement 91'in iixed position relative to the wheel body 81.,` y dY From the foregoing explanation, it should ,be evident that thegrinding wheel facing-91 may be supplied with a negative electricalcharge Without in any way charging the spindle, its bearings, orthecasing elements 13, 10, 8 and 9. Accordingly, the motor casing may be-iXed to the frame or bed 30 of the apparatus without the use ofelectrical insulation. The structure of Fig. 5Y will therefore embody'all the advantages and improvements specilied tor .the struct-ure ofFig. 4, including a maximum of safety in .operation due to theinsulating nature of the 'entire wheel body 81. The body 81 may .belfurnished any inclination including the full horizontal position, anddepending upon the nature .of the :operation'to be per'- tormed, thediamond wheel facing may be applied tothe rim of the grinding wheelrather than to the'llat tace thereof. f i i y 'libe Fig. 6 modiicationis illustrative of spindle structure such as might be employed lwhen thespindle is to carry two grinding Iwheels or discs 95 and 96. `VIntl1isinstance, two spindles 97 and 98 are aligned axially, with 7 their tailVends 99 `and v100 separated as shown, butcou- 4pled ,son uthat thespindles may rotate in unison. The spindles. are .hollow as Previouslyexplained, t @s99111- modat .elongate electric Current conductrslland-102 which ,are insulated romthewinner of the spindles. Condntors 101:and 10,2 may .0r may not abut 011@ er1- other Vendwise at their tail4end portions, c leplending upon whether .or not both wheels 95 and 96are t0 be @ladrically .charged Smultaneusly .That iS?..if..;ths.CQ.I.1..111.t0rS 101 arid .10.2 are t0 be. individual! abstenir the .tail endsof the conductors wopldfbe spaced fromone another, and .negative Chargesfrom separat@ .Sources Of electrical energy Could lie .Supplied t0 @ach`intiivduilly by yWay of brushssllt 1104 wiping the metalli@ discs 0r105m@ 'lseuredrespectively, to therods of condustOfS 101.1 and .10.2,The dises .0r drums 105 and 106 may be Separatedrhyscally andelectrically by an insulating disc 107, as shown.

",Thefcharaters 10.8 and .169 indicate flanged @Dalers of dielectricmaterial, each bored as `at llltl and 1412 to snugly receive the spindleends, and such couplers may be keyed or otherwise secured to thespindles against relative rotation. The ilanges 113 of the ycouplers maybe ,bored to receive a series of bolts or other fasteners l14 Whgh slampthe discs .0r drums 10S-19.6, along with .the insulating disc 107,tightly between the flanges Qf the Couplers.- ;By this means, prequivalent Sirva-ture. the @mire ,assembly may be bound and unied forrotation asa single rigid spindlerstructure. As will beunderstood, thespindle sections `97-and 93 are to be journalled in bearings anywherealong their length, and rotation may berimparted'to eitherspindlesection by associating a motor therewith as in Fig l, or more simply, bysecuring `a driving pulley-to oneof the sections.

In the event thatboth grinding discs or wheels 95, 96 are to hechar-gedsimultaneously with electrical energy, the insulating hdisc 107 may beomitted -and/ or the oonductor rods 101, 102 may be -butted endwise oreven joined together at their tail ends. Otherwise stated, the conductorrod may be continuous from wheel 95 to wheel 9 6, affording theconductor rod two working ends, 'or wheel ends, 1 15 and 116. Theintermediate portion of lthe single rod which mounts the brush disc ordrum,

would then have to be considered the tail end or tail portion of theconductor rod, within the portent of the claims appended hereto. Itshould be understood that the conductors 117 and 118 transmit negativecharges to the brushes 103 and 104, originating preferably fromseparategenerators or sources of electrical energy.

I f only one wheel is to be used 'for Velectrolytic grind ing, leavingthe` other available for plain `or straight grinding, the Fig. 6structure may simply eliminate one of the conductor rods, such Vas 101,along with its conductive disc -105 and the brush 103 .associatedtherewith. Mere omission of rod 101 would of course produce the sameresult; or if desired, the brush 103 might simply be omitted or held outof contact with its cooperative disc 105.

At the locations 119 and 120, suitable electrical connections areprovided between therconductor means 101, 102, and their respectivegrinding wheels or discs 95, 96, these connections being in accordancewith the disclosures of Figs. l, 4 or 5, or any other approvedengineering practice. The space surrounding the conductor rods 101, 102,within the spindle sections, may accommodate insulating sleeves such asare indicated at 70 upon Figs. 4 and 5, if desired. Whether or not suchsleeves are in- ,eluded in the structure, however, the spindle bodiesare insulated from the charges passing through the conductor rods 101and 102, so that the spindles will carry no electrical charge, thisbeing one of the primary objectives of the instant invention as wasexplained in the Vdescription of Figs. 1 to A5, inclusive. The spindlesectiqns'of Fig. 6, when mounting the grinding wheels in accordance withFigs...4 and 5, .are fully insulatedfrom sletrialgharga The grindingwheel in some instances may be metalfaced o n the rim, rather than onthe flat side face thereof, and the*A shape of the wheel may be alteredas required, toV present various contours to the workpiece. Undercertain conditions, the vdiamond chips or particles may be eliminatedfrom the working face of the conductive wheel, without materially orobjectionably depreciating the effectiveness of the electrolytic shapingor grinding process. The foregoing and various 'other modifications andchanges in structural details of the apparatus may be resorted to,within the scope of the appended claims, without departing fromthespirit of the invention.

:What is claimed is:

l. An electrolytic grinder for shaping an electrically charged Vmetallic workpiece, comprising in combination, an elongate drivingspindle having a working end and a tail end, a casing including bearingmeansrrotatably supporting the spindle near the ends thereof, means atthe working end yof the spindle for supporting a current conductivegrindingwheel in close proximity to the charged workpiece, and electriccurrent conductive means electrically insulatedfrom the spindle, fordirecting an electric current from a terminal upon the tail end of thespindle directly to a portion of the grinding wheel, to impose thereon avcharge opposite in polarity to the charge upon the workpiece.

2. Apparatus for shaping a metallic workpiece by the electrolyticprocess, comprising in combination, an electric motor including alongitudinally bored rotary driving spindle having a working end and atail end, a grinding wheel nxed uponthe working end of the spindle forrotation therewith, said wheel including an electricity conductivefacing to move in close proximity to the workpiece as the spindlerotates the wheel, an electric current conductive elongate rod supportedin spaced substantial concentricity with the spindle -inside the borethereof, said rod having opposite ends disposed near the ends of thespindle., means electrically connecting the ,grinding -wheel facing tothe conductive rod at theworking end of the spindle, and means yforapplying to the workpiece, and to the rod at the tail end of thespindle,

electrical potentials of opposite polarities.

3. Apparatus for shaping a metallic workpiece by the electrolyticprocess, comprising in combination, an elec- -tric motor including anarmature and eld windings,

and a longitudinally bored rotary driving spindle having a working endand a tail end, the armature being iixed tothe spindle and embraced bythe field windings along Ya portion `of the spindle length, a grindingwheel fixed upon the working end of the spindle for rotation therewith,said wheel including an electrically conductive facing to move lin closeproximity to the workpiece as the spindle rotates the wheel, an electriccurrent conductive elongated rodsupported in spaced subtantialconcentricity with the spindle inside the bore thereof,'said rod havingopposite ends disposed near the ends of the spindle, means electricallyconnecting the grinding wheel facing to the conductive rod at theworking end of the spindle,

ydielectric means interposed between the conductive rod and the motorarmature for shielding the armature and field windings againstinterference emanating from the conductive rod when electricallycharged, and means for applying to the workpiece, and to the rod at thetail end of the spindle, electrical potentials of opposite polarities.

4. Apparatus as specified in claim 3, wherein the current conductiveelongate rod is insulated from the material of the yspindle throughoutthe full length of the spindle.

5. Apparatus for shaping a metallic workpiece by the electrolyticprocess, comprising in combination, an electric motorincluding Valongitudinally bored rotary driving spindle having a working end and atail end, a grinding wheel fixed upon the working end of the spindle forrotation therewith, said wheel including an` electricallyconductiveafa'cing armored with spaced and extending dielectricmaterial, Yto contact the workpiece, an electric 4current conductiveelongatedmd supported within the spindle bore in an electricallyinsulated relationship to the spindle, said rod having opposite endsdisposed near the ends of the spindle, means electrically connecting thegrindingwheel facing to the conductive rod at the working end of thespindle, and means for applying to the workpiece, and to the rod at'thetail end of the spindle, electrical potentials fof opposite polarities.

6. Apparatus for shaping a metallic workpiece by the electrolyticprocess, comprising in combination, an electric motor including alongitudinally bored rotary driving spindle having a working end and atail end, a grinding wheel xed upon the working end of the spindle forrotation therewith, said wheel including an electrically conductivefacing to move in close proximity to the workpiece as the spindlerotates the wheel, an electric current conductive elongated rodsupported within the spindle bore in electrically insulatedrelationshipto the spindle, said rod having opposite ends disposed nearthe ends of the spindle, means electrically connecting the grindingwheel facing to the conductive rod at the Working end of the spindle,and means for applying to the workpiece, and to the rod at the tail endof the spindle, electrical potentials of opposite polarities.

7. In an electrolytic grinder, the combination which comprises, alongitudinally bored rotary driving spindle having a working end and atail end, a grinding wheel detachably fixed upon the working end of thespindle for rotation therewith, said wheel including an electricallyconductive facing to move in close proximity to an electrically chargedobject subject to grinding, an elongate electric current conductordisposed inside the spindle bore, and means electrically insulating saidconductor from the material of the spindle, said conductor having anopposite electric charge to the wheel through the agency of `a conductorpassing through the spindle bore from end to end thereof, electriccurrent supply being directed from said conductor at that end thereofwhich opposite ends disposed near the ends of the spindle, meanselectrically connecting the grinding wheel facing-to said conductor atthe working end of the spindle, a casing for the spindle, bearing meansin the casing for rotationally supporting the spindle, and means forapplying to the conductor at the tail end of the spindle, an electricalpotential opposite in polarity to that of the electrically chargedobject.

8. An electrolytic grinder for shaping an electrically chargedmetallic'workpiece, comprising in combination, a casing includingbearing means,V a longitudinally bored driving spindle rotatablysupported by the bearing means, said spindle having a working end and atail end, a grinding wheel iixed upon the working end of the spindle forrotation therewith, said wheel including an electrically conductivefacing to move in close proximity to the workpiece as the spindlerotates the wheel, an elongated electric current conductorsupported inspaced substantial concentricity with the spindle inside the borethereof, said conductor having opposite ends disposed near the ends lofthe spindle, means electrically connecting the grinding wheel facing tothe conductor aforesaid at the working end of the spindle, and means forapplying to said conductor at the tail end of the spindle, an electricalpotential opposite in polarity to that of the charged workpiece.

9. The method of electrolytically grinding a metallic electricallycharged workpiece, with the use of a motor driving a bearing-supportedmetallic rotary spindle carrying a metallic grinding wheel, said methodincluding rotating the spindle and grinding wheel relative to thecharged workpiece, and transmitting to the wheel exclusively of thespindle, from a spindle-supported terminal remote'from the wheel, anelectrical potential opposite in polarity to that of the chargedworkpiece.

10. The method o'f electrolytically grinding an electrically chargedmetallic workpiece, with the use of a motor rotating a longitudinallybored metallic spindle carrying on one end thereof a metallic grindingwheel, said method comprising rotating the spindle and grinding wheelrelative to the charged workpiece, and supplying is remote from thegrinding wheel.

l1. An electrolytic grinding wheel comprising a cylindrical body boredaxially to receive a driving spindle, and having an electric currentconductive face for exposure to a workpiece, said body being annularlygrooved concentrically with the bore to provide an open-topped troughreceptive of liquid electrolyte, said trough at its base being vprovidedwith o'penings terminating at the conductive face of the wheel, todirect electrolyte from the trough continuously to said wheel face asthe wheel rotates.

. 12. A grinding wheel for application to apparatus for shaping ametallic workpiece by the electrolytic process, said wheel-comprising acylindrical body bored axially to'receive a driving spindle, and meansfor securing the spindle within said bore, the body being 'annularlygrooved concentrically with the bore to provide a trough receptive ofliquid electrolyte, said trough at 4its base being provided with jetopenings for releasing electrolyte from the trough as the wheel rotates,and an electric conductive facing on the wheel exposed to the workpiece,said jet openings terminating at said facing to direct electrolyte ontosaid facing.

13. A grinding wheel for application to apparatus for shaping a metallicworkpiece by the electrolytic process, said wheel comprising acylindrical body bored axially to receive a driving spindle, and meansfor securing the spindle within said bore, an electric currentconductive facing on the body for exposure to the workpiece, the bodybeing annularly grooved concentrically with the bore to provide a troughreceptive of liquid electrolyte, said trough being provided interiorlythereof with jet openings for releasing electrolyte from the trough asthe wheel rotates, the jet openings terminating at said facing to directelectrolyte thereto, and an armor of spaced dielectric particles on saidfacing extending outwardly therefrom, to entrain andk distribute theelectrolyte upon the workpiece. v

`14. The grinding wheel as set forth in claim 13, wherein the body ofthe wheel is composed substantially wholly of dielectric material.

15. 'Ihe method of electrolytically shaping a conductive electricallycharged workpiece, with the use of a motor driving a bearing-supportedmetallic rotary spindle carrying an electric current conductive shapingwheel, said method including rotating the spindle with the wheeldisposed in lclose proximity to the charged workpiece, and transmittingto the wheel exclusively of the spindle,

' from a spindle-supported terminal remote from the Wheel Working endand a tail end, and a longitudinally extending bore formed therein, ashaping Wheel fixed upon the working end of the spindle for rotationtherewith, said wheel including an electrically conductive facing tomove lin close proximity to the workpiece as the spindle rotates thewheel, an electric current conductive elongate rod supported inelectrically insulated spaced substantial concentricity with the spindleinside the bore thereof, said rod having opposite ends disposed near theends of the spindle, means electrically connecting the wheel facing tothe conductive rod at the working end of the spindle, and means forapplying to the workpiece and to the rod at the tail end of the spindle,electrical potentials of opposite polarities.

17. A grinding wheel for application to Vapparatus for shaping ametallic workpiece by the electrolytic process,

said wheel comprising a V substantially Ycylindrical body bored axiallyto receive a driving Vspin/die and'having an upper and a lower face,means 4for detachably securing the vspindle within said bore, anelectric current conductive facing-on the lower face of the Wheel toscrub a workpiece, means electrically insulating the `wheel body fromthe driving spindle, kand means `carried by the wheel body for directingan electrolytic liquid ltoward the ywheel facing, said last-mentionedmeans including an lannular trough formed in the upper sufaoe oi thewheel and having an open top, and atleast one jet passage extending fromthe lower portion of the trough to said lower Ysurface of 4the wheel,said ,jet passage thereby providing communicationbetween said trough andsaid lower surface of the wheel, said jet passage sloping from thebottom of said trough toward the outer periphery of said wheel so thatwhen the Wheel is in operative position, electrolyte from the troughwill feed to said `facing Vautomatically with the aid of gravity andcentrifugal force.

References Citedin the file of this patent UNITED STATES PATENTS 390,439Bradley Oct. 2, 1888 1,636,560 Hall July 19, 1927 1,720,731 Jones July16, 1929 2,526,423 Rudor Oct. 17, 1950 2,739,935 Kehl et al. Mar. 27,1956 2,741,594 Bowersett Apr. 10, 1956 2,798,846' Comstock July 9, 19572,826,540 Keeleric Mar. V11, 1958 OTHER REFERENCES Mueller: How to GrindCarb-ides Six Times as Fast, American Machinist, September 28, 1953,pages 122 and Keeleric: Elect-rolytic Grinding, Steel, vol. 130, No.3page 84, March 17, 1952.

1. AN ELECTROLYTIC GRINDER FOR SHAPING AN ELECTRICALLY CHARGED METALLICWORKPIECE, COMPRISING IN COMBINATION, AN ELONGATE DRIVING SPINDLE HAVINGA WORKING END AND A TAIL END, A CASING INCLUDING BEARING MEANS ROTATABLYSUPPORTING THE SPINDLE NEAR THE ENDS THEREOF, MEANS AT THE WORKING ENDOF THE SPINDLE FOR SUPPORTING A CURRENT CONDUCTIVE GRINDING WHEEL INCLOSE PROXIMITY TO THE CHARGED WORKPIECE, AND ELECTRIC CURRENTCONDUCTIVE MEANS ELECTRICALLY INSULATED FROM THE SPINDLE, FOR DIRECTINGAN ELECTRIC CURRENT FROM A TERMINAL UPON THE TAIL END OF THE SPINDLEDIRECTLY TO A PORTION OF THE GRINDING WHEEL, TO IMPOSE